Field of the Invention
The invention relates in general to a multimedia system and associated control method, and more particularly to a multimedia system and associated control method for transmitting multimedia data over a standard cable.
Description of the Related Art
High Definition Multimedia Interface (HDMI™) is a trademark of HDMI Licensing, LLC, and provides an all-digital image and sound transmission interface. HDMI is applicable to set-top boxes, DVD players, personal computers, television game consoles, integrated amplifiers, digital sound systems and televisions. HDMI is capable of simultaneously transmitting non-compressed audio and video signals, and significantly simplifies installation complications of system wires as the audio and video signals used the same cable.
An HDMI transceiver adopts Transition-Minimized Differential Signaling (TMDS™) technologies, and encodes audio and video signals into data packets as TMDS data, which is then transmitted through a TMDS data channel as well as a TMDS clock channel. Each TMDS data channel supports a transmission speed up to 6 Gbps. An HDMI transceiver may also learn image transmission and reception capabilities of others through Display Data Channels (DDC) by using I2C signals to establish a correct multimedia link. Further, HDMI at the same time selectively offers a Consumer Electronics Control (CEC) function, which supports a function of operating multiple audiovisual devices using one single remote controller through a CEC channel that a signal line provides. HDMI further provides a function of Audio Return Channel (ARC), which allows the sound played by a television channel to return to an amplifier of a sound system.
Universal Serial Bus (USB) is a serial port bus standard connecting a computer system to an external device, and is also an input/output interface standard that not only is extensively applied in information communication products such as personal computers and mobile devices but also expands functions to photographing equipments, digital televisions, set-top boxes, game consoles and other related fields. In the year 2014, the USB Implementers Forum (IF) published the USB3.1 connection interface design standard, which includes USB Type-C™ (commonly referred to as Type-C). One major feature of a Type-C connector compliant to the Type-C specification is that, the upper and lower sides of the Type-C connector appear identical, in a way that the Type-C connector may be plugged in both directions, i.e., reversibly and non-reversibly connected.
FIG. 1 shows pin definitions of a Type-C receptacle defined by the Type-C specification. One Type-C receptacle includes 12 pins at each of its upper and lower sides. The pins A1, A12, B1 and B12 serve as ground lines GND. The pins A4, A9, B4 and B9 serve as bus power lines VBUS. According to the Type-C specification, the pins A6 and B6 are positive differential signal lines D+, and the pins A7 and B7 are negative differential signal lines D− to serve as a USB2.0 channel for transmitting USB2.0-compatible differential signals. The pins A2 and A3 provide a pair of SuperSpeed differential signal lines SSTX1+ and SSTX1− serving as a SuperSpeed differential signal channel SSTX1 for transmitting digital data at a speed as high as up to 10 Gbps. The pins A11 and A10 provide another pair of SuperSpeed differential signal lines SSRX2+ and SSRX2− serving as a SuperSpeed differential signal channel SSRX2 for receiving digital data at a speed as high as up to 10 Gbps. Similarly, the pins B2 and B3 provide a pair of SuperSpeed differential signal lines SSTX2+ and SSTX2− serving as a SuperSpeed differential signal channel SSTX2; the pins B11 and B10 provide another pair of SuperSpeed differential signal lines SSRX1+ and SSRX1− serving as a SuperSpeed differential signal channel SSRX1.
The pins A8 and B8 are respectively sideband use signal lines SBU1 and SBU2 for transmitting non-USB signals. For example, they may be used to transmit analog audio signals.
The pins A5 and B5 respectively serve as configuration channels (CC) CC1 and CC2. Through the pins A5 and A6, or the configuration channels CC1 and CC2, the polarity of a Type-C plug may be detected, i.e., whether the Type-C plug is non-reversibly or reversibly connected to a Type-C receptacle. Further, an upstream-facing port (UFP) and a downstream-facing port (DFP) connected at two ends of a Type-C cable may determine powering capabilities of the bus power line VBUS and the ground line GND according to a voltage dividing result generated by respective pull-up and pull-down resistors. The Type-C specification also provides a Power Delivery (PD) technology. In the standard mode of the Type-C specification, electronic devices connected at the two ends of a Type-C cable are capable of converting the USB PD protocol to Bi-phase Mark Coding (BMC) signals that may be transmitted to each other through the configuration channel CC1 or CC2, hence completing the handshake of power transmission of the UFP and the DFP.
Many electronic devices are equipped with both a USB socket and an HDMI socket. For example, the former is for connecting to an external memory, and the latter is for connecting to a display device. Different sockets need different cables, and more cables frequently lead to messier peripheral physical cables of these electronic devices. As the transmission speed of a Type-C cable is far greater than the transmission speed of an HDMI cable, transmitting HDMI signals using a Type-C cable may be a feasible solution. Therefore, there is a need for a solution that transmits HDMI signals using a Type-C cable while maintaining numerous technologies that the Type-C specification provides.